A proppant is a solid material typically intended for delivery into a subterranean formation for the purpose of enhancing or maintaining the hydraulic conductivity of the subterranean formation. Proppant materials are often utilized to keep hydraulic fractures open following treatment with a fracturing fluid. Proppant materials require sufficient mechanical strength to withstand closure stresses and hold open a fracture, but also must be sufficiently permeable to allow release and conduction of gas or oil to the surface.
When proppant particles are crushed they generate fines, which can detrimentally reduce the permeability of the treated seam. In many circumstances, a primary challenge is disaggregated formation fines reducing proppant pack conductivity. Proppant materials of high strength can minimize proppant crushing and the generation of such fines. However, higher proppant strength typically requires a proppant material with a higher density, and such higher density proppant materials demand higher pumping rates and higher operating and material costs.
Proppant materials are also routinely utilized in hydraulic fracturing of coal reservoirs. Many coal reservoirs are geologically situated in ways that make it difficult to safely, economically, and environmentally mine the coal. In some situations, wellbores are drilled to allow the release of methane adsorbed to the coal, which only recovers the naturally produced methane. Conventional approaches for such extraction are limited to the recoverable amount of methane within the coalbed, and yields are often hampered by inability to adequately and economically draw down wells. The quantities of gas recovered are minimal as compared to the amount of coal remaining in the reservoir. Thus, despite high infrastructure investment involved in drilling and stimulating production, wells must be plugged and abandoned as methane production declines, leaving large amounts of existing hydrocarbons and latent hydrocarbons (solid coal) unexploited.